The efficiency of a standard four-cycle petroleum internal combustion engine is limited with respect to compression ratio and pre-ignition compression high pressure temperatures. This is because of the need to avoid pre-ignition temperatures close to the fuel's auto-ignition temperature threshold, beyond which the knocking effect will impair efficiency and reduce engine life. Since temperature of intake air in a standard four-cycle engine depends on the ambient temperature that can typically vary from −20° C. to +42° C., at full compression inside the engine cylinder, this ambient temperature range translates to a variance of about 120° C. in pre-ignition temperature. As a consequence of this pre-ignition temperature variance, standard four-cycle engines are typically limited to a low compression ratio (CR), a parameter that is the ratio of the entire engine cylinder volume divided by the combustion chamber volume. For engines using standard gasoline fuel, CR is typically not greater than 8, which limits engines pre-ignition compression pressure of not more than 15 Bars.
These temperature and pressure constraints of the standard four-cycle engine design not only reduce engine efficiency, but they also result in larger and heavier engines and impose restrictions on the type of fuel that these engines can combust without knocking.
The present invention proposes a four-cycle internal combustion engine design with a single or a multi-stage pre-cooled compression, for which we will use short term “CWPSC” engine (Combustion with Pre-Stage Compression). As will be explained herein, this design allows the temperature and pressure of intake air to the combustion cylinders to be tightly controlled, so that a much higher compression ratio and pre-ignition compression pressure can be achieved without approaching the auto-ignition threshold. Moreover, because this novel design can effectively regulate and set the maximum pre-ignition temperature of the fuel-air mixture, it can combust virtually any type of liquid hydrocarbon fuel without danger of knocking.
The four-cycle engine of the present invention, due to its much higher compression ratio, generates power equivalent to or greater than a standard four-cycle engine in a smaller and lighter engine and in an environment where all main engine parameters are under control for maximum output and efficiency.